package oj.hot100;


import javax.swing.tree.TreeNode;

public class 二叉树的最近公共祖先 {

     public class TreeNode {
          int val;
          TreeNode left;
          TreeNode right;
          TreeNode(int x) { val = x; }
      }
    public TreeNode lowestCommonAncestor(TreeNode root, TreeNode p, TreeNode q) {
        if(root == null) {
            return null;
        }
        if(p == root || q == root) {
            return root;
        }
        TreeNode leftTree = lowestCommonAncestor(root.left,p,q);
        TreeNode rightTree = lowestCommonAncestor(root.right,p,q);
        if(leftTree != null && rightTree != null) {
            return root;
        }else if(leftTree != null) {
            return leftTree;
        }else {
            return rightTree;
        }
    }
}
